1. Field of the Invention
The present invention relates to an image processing method and apparatus, and a recording medium storing a program for executing the method. More particularly, the present invention relates to an image processing method and apparatus capable of effectively reducing noise in an image, and a recording medium storing a program for executing the method.
2. Description of the Related Art
In general, an image processing apparatus displays an image from image data on a display unit by reproducing an image file stored in a storage medium. A digital photographing apparatus, which is a type of image processing apparatus, photographs a subject in a shooting mode, stores image data regarding the subject in a storage medium, reproduces an image file from the storage medium, and then displays an image from the image data on a display unit.
If image data stored in the storage medium contains noise data, the noise is also displayed on a display unit, when such an image processing apparatus displays an image from the image data by reproducing the image file, thereby degrading the quality of the displayed image. Thus, there is a need to either display the image on the display unit by using the image processing apparatus so that noise is not present in the image from the image data or to basically process the image data. Also, when image data is obtained using a digital photographing apparatus, which is a type of image processing apparatus, the image data needs to be processed in order for an image from the image data not to include noise and then be stored in a storage medium.
FIG. 1 is a conceptual diagram schematically illustrating a first image containing noise. Conventionally, a bilateral filter is used to remove noise from an image but the resolution of a resultant image obtained by applying the bilateral filter to the image is degraded although noise is reduced therein. That is, in general, a noise reduction filter, such as the bilateral filter, reduces noise to approximately zero by averaging or weight-averaging data of pixels in a region having a predetermined size on an assumption that noise is evenly distributed. An edge may be generally understood in an image as the boundary between two subjects or a crease in a subject's clothes. The difference between the data value (brightness value) of a pixel at such an edge and the data value (brightness value) of a neighboring pixel is greater than the difference between the data values of adjacent pixels in a part of an image other than the edge. Thus, if the noise reduction filter is simply applied to the image, the difference between the data values of the pixel at the edge and the neighboring pixel decreases, thereby lowering the resolution of the image. FIG. 2 is a conceptual diagram schematically illustrating an image obtained by applying a noise reduction filter to the first image of FIG. 1. Referring to FIG. 2, the texture of the clothes (knitwear) of a woman who is a subject is greatly degraded as shown.